Adaptive load prediction for interference suppression receivers

Patent metadata

Field	Value
Publication number	US-9320053-B2
Application number	US-201113314775-A
Country	US
Kind code	B2
Filing date	Dec 8, 2011
Priority date	Dec 10, 2010
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

Load measurements having low computational complexity are provided that give an effective load after interference suppression. The effective load after interference may be compared with the air interface load to determine interference suppression gains for different user constellations. The interference suppression gains may be stored in the form of a gain table that gives the expected interference suppression gains for different user constellations. The expected interference suppression gains may be used by a scheduler at a base station to predict the effective load for two or more candidate user constellations, and to select one of the candidate user constellations. Users are then scheduled according to the selected user constellation.

First claim

What is claimed is:

1. A method of scheduling uplink transmissions from a plurality of users to a base station in a wireless communication network, the method comprising:
estimating interference suppression gains in received signals for two or more candidate user constellations defined by number of users and corresponding data rates;
computing predicted loads for a scheduling interval for each of the two or more candidate user constellations as a function of the estimated interference suppression gains for the candidate user constellations;
selecting one of the candidate user constellations for the scheduling interval based on the predicted loads
scheduling uplink transmissions from a set of users according to the selected user constellation.

2. The method of claim 1 wherein scheduling the uplink transmissions from the set of users according to the selected user constellation comprises scheduling a predetermined number of users and assigning corresponding bit rates to the scheduled users according to the selected user constellation.

3. The method of claim 1 wherein computing the predicted loads for at least one scheduling interval for each of the two or more candidate user constellations comprises:
computing predicted air interface loads for each of the candidate user constellations; and
adjusting the predicted air interface loads based on corresponding interference suppression gains for the candidate user constellations to obtain the predicted loads for each candidate user constellation.

4. The method of claim 1 wherein estimating interference suppression gains for two or more candidate user constellations comprises obtaining predetermined interference suppression gains for the two or more candidate user constellations from a gain table stored in memory of the base station.

5. The method of claim 4 wherein the predetermined interference suppression gains comprise average interference suppressions gains for the two or more candidate user constellations over a plurality of scheduling intervals.

6. The method of claim 4 further comprising interpolating interference suppression gains for one of the two or more candidate user constellations with no corresponding interference suppression gain in the gain table.

7. The method of claim 5 further comprising updating the gain table to include information for a current scheduling interval by recomputing one or more of the predetermined interference suppression gains.

8. The method of claim 7 wherein recomputing one or more of the predetermined interference suppression gains comprises:
determining a current user constellation for the current scheduling interval;
computing an interference suppression gain for the current user constellation; and
recomputing the average interference suppression gain for the current user constellation to include the interference suppression gain for the current scheduling interval.

9. The method of claim 8 wherein determining a current user constellation for the current scheduling interval comprises:
determining a number of users transmitting data on the uplink in the current scheduling interval; and
determining the transport formats for the users transmitting data on the uplink in the current scheduling interval.

10. The method of claim 8 wherein computing the interference suppression gain for the current user constellation comprises computing a difference between an uplink load before interference suppression and an uplink load after interference suppression.

11. The method of claim 10 wherein computing a difference between the uplink load before interference suppression and the uplink load after interference suppression comprises:
computing rise over thermal before interference suppression and rise over thermal after interference suppression;
computing a load factor before interference suppression from the computed rise over thermal before interference suppression;
computing a load factor after interference suppression from the computed rise over thermal after interference suppression; and
computing a difference between the load factor before interference suppression and the load factor after interference suppression.

12. The method of claim 11 wherein computing load factors before and after interference suppression comprises:
estimating neighbor cell interference and thermal noise;
computing the load factor before interference suppression as a function of the neighbor cell interference, thermal noise, and rise over thermal before interference suppression; and
computing the load factor after interference suppression as a function of the neighbor cell interference, thermal noise, and rise over thermal after interference suppression.

13. The method of claim 10 wherein computing the difference between the uplink load before interference suppression and the uplink load after interference suppression comprises:
computing rise over thermal before interference suppression and rise over thermal after interference suppression; and
computing a difference between the rise over thermal before interference suppression and the rise over thermal after interference suppression.

14. The method of claim 13 wherein the rise over thermal after interference suppression is computed as the maximum rise over thermal for the users in the current user constellation.

15. The method of claim 1 wherein the interference suppression gains represent the gain as a fraction of a total cell load.

16. The method of claim 1 further comprising computing a variance of the interference suppression gain for each user constellation, wherein the computation of the predicted load is further based on the variance of the interference suppression gain.

17. The method of claim 1 further comprising scheduling the users in a plurality of recurring time slots in a time division multiplexing transmission scheme.

18. The method of claim 17 wherein predicted loads for a plurality of candidate user constellations are computed for each time slot, and wherein users are scheduled in each time slot according to a selected one of the candidate user constellations for each time slot based on the predicted loads.

19. A base station in a wireless communication network, the base station comprising:
an interference suppression receiver to suppress interference in received signals from a plurality of users; and
a control circuit including a scheduler for scheduling uplink transmissions from the users, the scheduler being configured to:
estimate interference suppression gains in received signals for two or more candidate user constellations defined by number of users and corresponding data rates;
compute predicted loads for a scheduling interval for each of the two or more candidate user constellations as a function of the estimated interference suppression gains for the candidate user constellations;
select one of the candidate user constellations for the scheduling interval based on the predicted loads; and
schedule uplink transmissions from a set of users according to the selected user constellation.

20. The base station of claim 19 wherein the scheduler is configured to schedule a set of users by:
scheduling a predetermined number of users; and
assigning corresponding bit rates to the scheduled users according to the selected user constellation.

21. The base station of claim 19 wherein the scheduler is configured to compute predicted loads for at least one scheduling interval for each of the two or more candidate user constellation

Assignees

• Wigren Karl Torbjörn
• Ericsson Telefon Ab L M

Inventors

• Wigren Karl Torbjörn

Classifications

• H04W72/52

  based on load · CPC title

• H04W72/1268 Primary

  of uplink data flows · CPC title

• H04W72/1252

  Electricity · mapped topic